This invention relates to an outboard motor and more particularly to a reduction drive transmission for an outboard motor.
Relative low horsepower outboard motors are frequently employed as auxiliary power plants for sailboats. By low power, this generally means that the horsepower employed for such applications is something in the neighborhood of 10 horsepower or less. With these low horsepowers, however, the acceleration from standstill to the desired cruising speed can be quite slow. Also, in some instances the engine may not provide sufficient power to achieve the desired speeds.
Although this problem can be somewhat reduced by using a higher reduction ratio in the gear drive from the engine to the propeller, the desire to keep the lower unit, where the transmission resides, small generally limits the reduction ratio in the range of 1.8 to 2.4 to 1. Larger reduction ratios require bevel gears of larger diameters and this will produce a protracted lower unit. As the lower unit size increases, the hydrodynamic drag increases and thus, some of the advantage of the reduced gear ratio will be lost by the increased drag.
It is, therefore, a principal object of this invention to provide an improved marine drive transmission useable with outboard motors to provide a gear reduction greater than the bevel gear of the lower unit and which transmission is located so that it will not increase the size of the lower unit.
It is a further object of this invention to provide an improved reduction gear transmission for outboard motor that does not increase hydrodynamic drag.